Yellow Head Virus Research Articles

Molecular characterization of a short-chained pentraxin gene from kuruma shrimp Marsupenaeus japonicus hemocytes

Pentraxins (PTXs) are a family of pattern recognition proteins (PRPs) that play a role in pathogen recognition during infection via pathogen-associated molecular patterns (PAMPs). Here, we characterized a short-chained pentraxin isolated from kuruma shrimp (Marsupenaeus japonicus) hemocytes (MjPTX). MjPTX contains the pentraxin signature HxCxS/TWxS (where x can be any amino acid), although the second conserved residue of this signature differed slightly (L instead of C). In the phylogenetic analysis, MjPTX clustered closely with predicted sequences from crustaceans (shrimp, lobster, and crayfish) displaying high sequence identities exceeding 52.67 %. In contrast, MjPTX showed minimal sequence identity when compared to functionally similar proteins in other animals, with sequence identities ranging from 20.42 % (mouse) to 28.14 % (horseshoe crab). MjPTX mRNA transcript levels increased significantly after artificial infection with Vibrio parahaemolyticus (48 h), White Spot Syndrome Virus (72 h) and Yellow Head Virus (24 and 48 h). Assays done in vitro revealed that recombinant MjPTX (rMjPTX) has an ability to agglutinate Gram-negative and Gram-positive bacteria and to bind microbial polysaccharides and bacterial suspensions in the presence of Ca2+. Taken together, our results suggest that MjPTX functions as a classical pattern recognition protein in the presence of calcium ions, that is capable of binding to specific moieties present on the surface of microorganisms and facilitating their clearance.

Determining patterns of tissue tropism for IHHNV, GAV and YHV-7 infection in giant black tiger shrimp (Penaeus monodon) using real-time RT-qPCR

Disease management in shrimp aquaculture is heavily dependent on accurate and rapid pathogen detection and diagnosis. Understanding the presence and distribution of pathogens within various tissues of the shrimp host is critical to ensure detection efforts are targeted for optimal sensitivity and reliability. Modern advancements in molecular technologies, including nucleic acid extraction and RT-qPCR, have yielded significant improvements in pathogen detection capabilities. Despite these advancements and their widespread adoption within both research and industry applications, evidence to inform their optimised use, such as revisions to tissue-specific viral detection to support selection of appropriate target tissues, has not been established. To address these gaps, this study aimed to establish contemporary evidence of viral tissue tropism for three major shrimp pathogens. TaqMan qPCR analysis was used to determine tissue-specific loading of viral pathogens in naturally infected Penaeus monodon pleopod, gill, hepatopancreas, lymphoid organ, abdominal muscle tissue, hindgut and ventral nerve cord. The viral targets analysed included Penaeus stylirostris penstyldensovirus 1 (PstDV1), formerly named infectious hypodermal haematopoietic necrosis virus (IHHNV) and, two genotypes of the yellow head virus complex, including genotype 2 known as gill associated virus (YHV-2/ GAV), and genotype 7 (YHV-7). QPCR analyses demonstrated the highest level of genetic IHHNV detection from gill tissue, followed sequentially by hindgut, pleopod, hepatopancreas, lymphoid organ, ventral nerve cord and abdominal muscle. For the yellow head viruses (GAV and YHV-7), no significant differences in genetic viral detection were demonstrated, although a non-significant advantage was observed for lymphoid organ and hindgut tissue. Beyond establishing contemporary evidence of viral distribution to improve understanding of host-viral interactions, these findings offer supporting evidence for revisions to appropriate target tissue recommendations, within the World Organisation for Animal Health (WOAH, founded as OIE) Manual of Diagnostic Tests for Aquatic Animals, for optimised modern shrimp pathogen detection.

Development of a multiplex real-time enzymatic recombinase amplification assay for differentiation of yellow head virus genotype 1 and 2 in Penaeus vannamei

At present, eight genotypes of yellow head virus (YHV) have been identified, and the main pathogenic genotypes are yellow head virus 1 (YHV1) and gill-associated virus (GAV), which have caused mass death and serious economic losses of shrimp industry. The prevention of YHV complex infection is highly dependent on early and rapid diagnostic, however, the available molecular technologies require complex procedures or expensive equipment. In this study, a multiplex rapid detection method of YHV1 and GAV based on real-time enzymatic recombinase amplification (YHV1/GAV-ERA) was established. Primers and probes were designed to detect the conserved ORF1b gene of YHV1 and GAV. Best primers and probes were selected to effectively amplify the target gene, and the sensitivity was reached 102 copies/μL within 6.17 ± 0.49 min. While multi-nested PCR could reach the detection limit of 1.9 copies/μL and 2.1 copies/μL for YHV1 and GAV by consuming higher time and instrument cost. The YHV1/GAV-ERA can effectively amplify the target gene at 32–45 °C within 30 min, and the optimum reaction temperature is 42 °C. No cross reaction with white spot syndrome virus (WSSV), Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease (VpAHPND), Enterocytozoon hepatopenaei (EHP), infectious hypodermal and hematopoietic necrosis virus (IHHNV) and healthy shrimp DNA were observed. Additionally, the test results of YHV1/GAV-ERA were 100% consistent with the industrial standard multi-nested PCR in shrimp samples. This method can distinguish the two genotypes of YHV and get rid of the dependence on the thermal cycle instrument, and provides a feasible rapid detection method for on-site screening of pathogens.

Stock Health of Penaeid Shrimps in Sri Lanka: a Comprehensive Molecular-Based Study on Seven Diseases Found in the Asian Region

Purpose: Although shrimp aquaculture in Sri Lanka has mainly been plagued by recurrent outbreaks of White Spot Syndrome Virus (WSSV), recent symptomatic and analytical field data of shrimps were incoherent with typical WSSV infections. As transboundary infection of new diseases is not uncommon in world shrimp aquaculture, the possibility of new diseases established in the country surfaced. Hence, the present study was aimed at evaluating the stock health of shrimps in Sri Lanka for additional six diseases commonly available in the Asian region, namely Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV), Infectious Myonecrosis Virus (IMNV), Taura Syndrome Virus (TSV), Yellow Head Virus (YHV), Acute Hepatopancreatic Necrosis (AHPND) and Necrotizing Hepatopancreatitis Bacterium (NHPB). Research method: Sampling was performed using broodstocks, postlarvae, cultured Penaeus monodon, wild P. semisulcatus, P. indicus and P. monodon from different locations and broodstock collecting areas in the country. Other crustacean species were also collected as possible carrier species. The presence of pathogenic organisms was identified by Polymerase Chain Reaction using respective IQ 2000TM test kits and a total of 2060 PCR tests were conducted. Findings: Of all the samples tested, no samples were positive for IMNV, TSV, YHV, AHPND and NHPB. However, confirmatory evidence was found in Sri Lanka for the presence of IHHNV with the prevalence of 31.3% in broodstock samples, 24.07% in hatchery-produced postlarvae and 18.03% in cultured shrimps. WSSV was also recorded with a prevalence of 10.34% in broodstock samples and 55.56% in cultured shrimp samples collected. None of the wild collected samples was positive for any of the tested diseases. Value: Reinstating the presence of WSSV in the Sri Lankan shrimp industry, provides confirmatory evidence of the presence of IHHNV in the country, highlighting the possibility of the emergence of new diseases in shrimp farming in Sri Lanka. Also, commonly suggested disease carriers seem to be not the major cause of disease spread during the sampling time. This study, therefore, provides much-needed information about the stock health of shrimps in Sri Lanka.

Identification of immune-responsive circular RNAs in shrimp (Litopenaeus vannamei) upon yellow head virus infection

Circular RNAs (circRNAs) are a subclass of non-coding RNAs (ncRNAs) formed through a process known as back-splicing. They play a crucial role in the genetic regulation of various biological processes. Currently, circRNAs have been identified as participants in the antiviral response within mammalian cells. However, circRNAs in shrimp infected with the yellow head virus (YHV) remain largely unexplored. Therefore, this study aims to identify circRNAs in the hemocytes of Litopenaeus vannamei during YHV infection. We discovered 358 differentially expressed circRNAs (DECs), with 177 of them being up-regulated and 181 down-regulated. Subsequently, eight DECs, including circ_alpha-1-inhibitor 3, circ_CDC42 small effector protein 2, circ_hemicentin 2, circ_integrin alpha V, circ_kazal-type proteinase inhibitor, circ_phenoloxidase 3, circ_related protein rab-8B, and circ_protein toll-like, were randomly selected for analysis of their expression patterns during YHV infection using qRT-PCR. Furthermore, the circRNAs' characteristics were confirmed through PCR, RNase R treatment, and Sanger sequencing, all of which were consistent with the features of circRNAs. These findings contribute to a better understanding of circRNAs’ involvement in the antiviral response in shrimp.

Nucleic acid amplification‐based methods for diagnosis of shrimp viral diseases

AbstractViral diseases are one of the constraints affecting the sustainability of the shrimp farming industry worldwide. The common causes of viral infections include white spot syndrome virus, infectious hypodermal and haematopoietic necrosis virus, hepatopancreatic parvovirus, Penaeus monodon nudivirus, decapod iridescent virus 1, Taura syndrome virus, yellow head virus, infectious myonecrosis virus and Macrobrachium rosenbergii nodavirus. Accurate diagnostic methods are necessary for preventing the spread of these transboundary diseases. Many molecular diagnostic methods for shrimp viral diseases have been developed and are currently in use, including conventional polymerase chain reaction (PCR), nested PCR, loop‐mediated isothermal amplification PCR, recombinase polymerase assay and real‐time PCR. Although the World Organization for Animal Health (founded as OIE) recommends several PCR methods for shrimp disease diagnosis, there has been a lack of efforts to comparatively evaluate the performance of the available methods, resulting in a significant knowledge gap. Therefore, in this review, we compare various PCR assays and commercial PCR‐based diagnostic kits that have been developed and/or published previously, and discuss pros and cons of each of these methods. Our objective of this review is to offer enhanced clarity and a comprehensive overview of molecular diagnostic methods for shrimp viral diseases. This endeavour would serve as an important resource for researchers engaged in relevant studies and professionals within the shrimp‐farming industry, providing valuable guidance and insights.

A multiplex real-time polymerase chain reaction (qPCR) kit targeting VP664 and VP28 genes of white spot syndrome virus (WSSV)

The implementation of a precise and sensitive detection method is crucial to prevent the spread of the white spot syndrome virus (WSSV) within and between regions. The present study developed and validated the analytical and diagnostic performances of a multiplex real-time polymerase chain reaction kit (AccuPower® WSSV detection qPCR kit: AWqPCR kit) that simultaneously detects two distinct genomic sequences of WSSV (VP664 and VP28). The analytical sensitivity of the kit, defined as 95% limit of detection (LoD95%), was 1.15 copies of WSSV plasmid. No cross-reactivity was found against five shrimp pathogens (yellow head virus genotype 1, Taura syndrome virus, infectious myonecrosis virus, infectious hypodermal and hematopoietic necrosis virus, and Vibrio parahaemolyticus). Moreover, no significant PCR inhibition was observed while using nine potential interfering materials (antibiotics and immunostimulants). Diagnostic performance was evaluated using 200 known WSSV-infected whiteleg shrimp (Litopenaeus vannamei). Compared to the IQ2000™ WSSV Detection and Prevention System (IQ2000™ WSSV DPS), the diagnostic sensitivity (Dsn) and specificity (Dsp) of the AWqPCR kit were found to be 100% (95% confidence interval (CI): 96.38–100%) and 100% (95% CI: 96.38–100%), respectively. In addition, using 50 shrimp samples of unknown WSSV infection status, the Dsn and Dsp of the AWqPCR kit were compared to the two available gold standard WSSV detection methods, including the qPCR assay using WOAH primers and probe (WOAH qPCR) and IQ2000™ WSSV DPS. The evaluated Dsn and Dsp of the kit were 100% (95% CI: 87.66–100%) and 72.73% (95% CI: 49.78–89.27%) compared to the WOAH qPCR, whereas the Dsn and Dsp were 100% (95% CI: 25–100%) and 32.65% (95% CI: 19.95–47.54%) when compared to the IQ2000™ WSSV DPS. All six samples that were detected as WSSV-positive by the AWqPCR kit and confirmed by sequencing were found to be WSSV-negative by WOAH qPCR. Furthermore, the blind sample analysis of 50 shrimp samples carried out by three laboratories showed no significant difference in the test results. Overall, AWqPCR kit was found to be a simple and reliable method for WSSV detection with high sensitivity and specificity. Therefore, it could be applied in quarantine, surveillance, and monitoring programmes as well as for the confirmation of WSSV in apparently healthy shrimps.

Species which may act as vectors or reservoirs of diseases covered by the Animal Health Law: Listed pathogens of crustaceans.

Vector or reservoir species of three diseases of crustaceans listed in the Animal Health Law were identified based on evidence generated through an extensive literature review, to support a possible updating of Regulation (EU) 2018/1882. Crustacean species on or in which Taura syndrome virus (TSV), Yellow head virus (YHV) or White spot syndrome virus (WSSV) were identified, in the field or during experiments, were classified as reservoir species with different levels of certainty depending on the diagnostic tests used. Where experimental evidence indicated transmission of the pathogen from a studied species to another known susceptible species, the studied species was classified as vector species. Although the quantification of the risk of spread of the pathogens by the vectors or reservoir species was not part of the terms of reference, such risks do exist for the vector species, since transmission from infected vector species to susceptible species was proven. Where evidence for transmission from infected crustaceans was not found, these were defined as reservoirs. Nonetheless, the risk of the spread of the pathogens from infected reservoir species cannot be excluded. Evidence identifying conditions that may prevent transmission by vectors during transport was collected from scientific literature. It was concluded that it is very likely to almost certain (90-100%) that WSSV, TSV and YHV will remain infective at any possible transport condition. Therefore, vector or reservoir species that may have been exposed to these pathogens in an affected area in the wild or aquaculture establishments or by water supply can possibly transmit WSSV, TSV and YHV.

CRISPR-based, genotype-specific detection of yellow head virus genotype 1 with fluorescent, lateral flow and DNAzyme-assisted colorimetric readouts

The yellow head virus complex comprises 8 genotypes of single-stranded RNA viruses infecting penaeid shrimp, but only yellow head virus genotype 1 (YHV1) is capable of causing massive shrimp mortalities and severe economic losses. However, current molecular techniques could not detect YHV1 with high specificity, or require complicated protocols for this purpose. Here, we developed a combination of reverse-transcriptase recombinase polymerase amplification (RT-RPA) and CRISPR-Cas detection (“RR-Cas”) for the genotype-specific detection of YHV1. The method can be completed within 1.5 h at a constant temperature near 37 °C, after which the results can be visualized by the naked eye using fluorescent, lateral flow, and G-quadruplex DNAzyme-assisted colorimetric assays. The detection limit is 100 copies of plasmid DNA and 100 fg of total RNA from YHV1 infected shrimp, comparable to the WOAH-recommended one-step RT-PCR protocol. In the evaluation of clinical samples, RR-Cas was found to be less sensitive than nested RT-PCR, but displayed superior specificity, yielding no false positive results towards samples containing YHV2 and 3. Overall, our findings suggest that RR-Cas is a powerful addition to the toolkit for genotype-specific viral diagnosis in shrimp aquaculture, with the potential to greatly streamline disease surveillance and management in the shrimp industry.

In silico screening of chalcones and flavonoids as potential inhibitors against yellow head virus 3C-like protease.

Yellow head virus (YHV) is one of the most important pathogens in prawn cultivation. The outbreak of YHV could potentially result in collapses in aquaculture industries. Although a flurry of development has been made in searching for preventive and therapeutic approaches against YHV, there is still no effective therapy available in the market. Previously, computational screening has suggested a few cancer drugs to be used as YHV protease (3CLpro) inhibitors. However, their toxic nature is still of concern. Here, we exploited various computational approaches, such as deep learning-based structural modeling, molecular docking, pharmacological prediction, and molecular dynamics simulation, to search for potential YHV 3CLpro inhibitors. A total of 272 chalcones and flavonoids were in silico screened using molecular docking. The bioavailability, toxicity, and specifically drug-likeness of hits were predicted. Among the hits, molecular dynamics simulation and trajectory analysis were performed to scrutinize the compounds with high binding affinity. Herein, the four selected compounds including chalcones cpd26, cpd31 and cpd50, and a flavonoid DN071_f could be novel potent compounds to prevent YHV and GAV propagation in shrimp. The molecular mechanism at the atomistic level is also enclosed that can be used to further antiviral development.

Coinfection with Yellow Head Virus Genotype 8 (YHV-8) and Oriental Wenrivirus 1 (OWV1) in Wild Penaeus chinensis from the Yellow Sea.

At present, there are few studies on the epidemiology of diseases in wild Chinese white shrimp Penaeus chinensis. In order to enrich the epidemiological information of the World Organisation for Animal Health (WOAH)-listed and emerging diseases in wild P. chinensis, we collected a total of 37 wild P. chinensis from the Yellow Sea in the past three years and carried out molecular detection tests for eleven shrimp pathogens. The results showed that infectious hypodermal and hematopoietic necrosis virus (IHHNV), Decapod iridescent virus 1 (DIV1), yellow head virus genotype 8 (YHV-8), and oriental wenrivirus 1 (OWV1) could be detected in collected wild P. chinensis. Among them, the coexistence of IHHNV and DIV1 was confirmed using qPCR, PCR, and sequence analysis with pooled samples. The infection with YHV-8 and OWV1 in shrimp was studied using molecular diagnosis, phylogenetic analysis, and transmission electron microscopy. It is worth highlighting that this study revealed the high prevalence of coinfection with YHV-8 and OWV1 in wild P. chinensis populations and the transmission risk of these viruses between the wild and farmed P. chinensis populations. This study enriches the epidemiological information of WOAH-listed and emerging diseases in wild P. chinensis in the Yellow Sea and raises concerns about biosecurity issues related to wild shrimp resources.

Failed shrimp vaccination attempt with yellow head virus (YHV) attenuated in an immortal insect cell line

This short paper on yellow head virus Type-1 (YHV-1) of shrimp describes preliminary research on the potential for using YHV-1 attenuated in insect cells to protect shrimp against yellow head disease (YHD). YHV-1 can cause severe mortality in the cultivated shrimp Penaeus (Penaeus) monodon and Penaeus (Litopenaeus) vannamei. No practical vaccination has been reported. The C6/36 mosquito cell cultures inoculated with YHV-1 become positive by PCR and by immunocytochemistry (immunopositive) for up to 30 split-cell passages. Shrimp injected with homogenates from low-passage cultures die from typical YHV-1 disease while shrimp injected with homogenates from high passage cultures do not, even though they become PCR positive and immunopositive for YHV-1. This suggested that viral attenuation had occurred during insect-cell passaging, and it opened the possibility of using homogenates from high-passage insect cultures as a vaccine against YHV-1. To test this hypothesis, homogenates from 30th-passage, YHV-positive cultures were injected into shrimp followed by challenge with virulent YHV-1. Controls were injected with homogenate from 30th-passage, naive (normal stock) insect-cell cultures. No shrimp mortality occurred following injection of either homogenate, but shrimp injected with the YHV-1 homogenate became both RT-PCR positive and immunopositive. Upon challenge 10 days later with YHV-1, mortality in shrimp injected with naive insect-cell homogenate was 100% within 7 days post-challenge while 100% mortality in the YHV-1 homogenate group did not occur until day 9 post-challenge. Kaplan-Meier log-rank survival analysis revealed that survival curves for the two groups were significantly different (p < 0.001). The cause of delay in mortality may be worthy of further investigation.

Simultaneous Production of a Virus-Like Particle Linked to dsRNA to Enhance dsRNA Delivery for Yellow Head Virus Inhibition

A co-expressed Penaeus stylirostris densovirus (PstDNV) capsid and dsRNA specific to the yellow head virus (YHV) protease (CoEx cpPstDNV/dspro) has been shown to suppress YHV replication in the Pacific white-legged shrimp (Litopenaeus vannamei). However, maintaining two plasmids in a single bacterial cell is not desirable; therefore, a single plasmid harboring both the PstDNV capsid and the dsRNA-YHV-pro gene was constructed under the regulation of a single T7 promoter, designated pET28a-Linked cpPstDNV-dspro. Following induction, this novel construct expressed an approximately 37-kDa recombinant protein associated with a roughly 400-bp dsRNA (Linked cpPstDNV-dspro). Under a transmission electron microscope, the virus-like particles (VLP; Linked PstDNV VLPs-dspro) obtained were seen to be monodispersed, similar to the native PstDNV virion. A nuclease digestion assay indicated dsRNA molecules were both encapsulated and present outside the Linked PstDNV VLPs-dspro. In addition, the amount of dsRNA produced from this strategy was higher than that obtained with a co-expression strategy. In a YHV infection challenge, the Linked PstDNV VLPs-dspro was more effective in delaying and reducing mortality than other constructs tested. Lastly, the linked construct provides protection for the dsRNA cargo from nucleolytic enzymes present in the shrimp hemolymph. This is the first report of a VLP carrying virus-inhibiting dsRNA that could be produced without disassembly and reassembly to control virus infection in shrimp.

Sistem Pakar Diagnosa Penyakit Udang Vannamei Menggunakan Metode Forward Chaining Berbasis Web (Studi Kasus : Petambak Udang Dirawajitu)

One of the causes of failure in pond shrimp farming is disease. The most dangerous disease attacks and causing losses to farmers are due to viral attacks of Myo/Infectious Myo Necrosis Virus (IMNV) of Shrimp, White Spot Syndrome (WSS) of Shrimp, Early Mortality Syndrome (EMS), and Yellow Head Disease. / Yellow Head Disease. The purpose of the research is to build an expert system application that can diagnose pond shrimp disease using the backward chaining method so as to help the community in Rawajitu sub-district in aquaculture shrimp., the system design method used is Unified Modeling Language (UML), the system development method used is Waterfall, and system built using Adobe Dreamweaver 8 tools and MySQL database. The results of this study are the application of an expert system that can diagnose pond shrimp disease using the backward chaining method. The system created later is expected to provide services to shrimp farmers in obtaining information on shrimp disease and accurate disease management solutions.

Environmental and Socioeconomic Impacts of Shrimp Farming in the Philippines: A Critical Analysis Using PRISMA

Shrimp aquaculture is under pressure to increase its production to meet the growing demand for food from a growing population. In the Philippines, aquaculture has experienced the shift from milkfish to prawn, with its attractive marketable price. This intensification has led to negative and positive impacts, which have raised a range of environmental and socioeconomic problems. This paper reviews the environmental and socioeconomic challenges that the shrimp aquaculture industry faces using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method. We examine the gaps and the changes that are required to revitalize the industry. We examine and assess the impacts of shrimp culture on the environment, e.g., shrimp farm management, marine pollution, disease outbreaks, and the social, economic, and climate change impacts. The presence of viral diseases, such as White Spot Syndrome Virus (WSSV), Monodon Baculovirus (MBV), Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV), Hepatopancreatic Parvovirus (HPV), and Yellow Head Virus (YHV), have caused approximate losses in the industry of 40,080 mt in 1997, and 51,000 mt in 2014. Recommended strategies and policy changes are considered for the improvement of shrimp aquaculture, including disease management, the adoption of good aquaculture practices, proper environmental monitoring, sustainable practices at the farm level, and priorities for cooperation among the concerned government agencies and local governments, as well as the involvement of state universities and colleges, for better management practices.

Yellow head virus

This datasheet on yellow head virus covers Identity, Overview, Distribution, Hosts/Species Affected, Further Information.

Prevalence of disease outbreak from cultured whiteleg shrimp Penaeus vannamei farms located in Karnataka, India

Penaeus vannamei farming is one of the profitable businesses of the aquaculture sector in India. As a result of excessive farming, shrimps were susceptible to various exotic, transboundary, and emerging pathogens. The purpose of this study is to monitor the prevalence of shrimp pathogens in Karnataka. A total of 91 samples of P. vannamei post larvae and juveniles were collected from April 2022 to November 2022 in Karnataka. Samples were screened for pathogens as listed in Office of Internationale des Epizootics (OIE) or World Organisation for Animal Health (WOAH) which include infectious hypodermal and hematopoietic necrosis virus (IHHNV), Enterocytozoon hepatopenaei (EHP), acute hepatopancreatic necrosis disease (AHPND), hepatopancreatic parvovirus (HPV), infectious myonecrosis virus (IMNV), yellow head virus (YHV), taura syndrome virus (TSV), white spot syndrome virus (WSSV), and other diseases such as decapod iridescent virus-1(DIV-1), and monodon baculovirus (MBV). Out of 91 samples, 5 (5.5%) samples were positive for WSSV, 26 (28.6%) samples were positive for EHP, and 2 (2.2%) samples had co-infection caused by EHP and WSSV. In this study, we have reported a high prevalence of EHP than WSSV in all three coastal districts of Karnataka. Farmers were using specific pathogen-free (SPF) seeds for culture but still, their cultures are getting infected with the same pathogens which indicates poor pond preparation and bio-security. So we strongly recommend that farmers have to follow good management practices and bio-security to increase the productivity and sustainability of P. vannamei farming in India.

Shrimp Vaccination with Insect-Adapted Yellow Head Virus (YHV) Extends Survival Upon YHV Challenge

Shrimp Vaccination with Insect-Adapted Yellow Head Virus (YHV) Extends Survival Upon YHV Challenge

Characterization of X- box binding protein 1(XBP1) and BiP functions and investigation their roles in YHV replication in P. monodon

Abstract Eukaryotic cells have mechanisms to cope with stress in endoplasmic reticulum (ER) called unfolded protein response (UPR). In this study, we characterized putative X-box DNA binding protein1 (XBP1) and Binding protein (BiP) cDNAs from black tiger shrimp (Peneaus monodon). When the shrimp were infected with Yellow head virus (YHV), the levels of XBP1 and BiP mRNA transcripts were elevated approximately 8 and 55 folds, respectively. In normal shrimp, the putative XBP1 (XBP1u) was predicted to encode a protein with 283 amino acid residues. When shrimp were infected with YHV, portion of cDNA with 17 nucleotides intron elimination (XBP1s) was observed. The elimination caused alteration of its translational frame. The predicted protein from this is 469 amino acids in length with total change in its amino acid sequence downstream of the intron. Functional analysis of these XBP1 proteins in mammalian cells clearly showed that overexpression of P. monodon XBP1s was capable of activating the transcription rate of mammalian UPR responsive genes (BiP, ERdj4 and P58IPK). Finally, the impact of XBP1 and BiP on YHV multiplication in black tiger shrimp was investigated by RNAi approach. Knocking down either XBP1 or BiP expression efficiently inhibited YHV replication. Therefore, these two components in the UPR pathway may be an interesting target for anti YHV development in the future. Keywords: Endoplasmic reticulum, siRNA, Stress-inducible genes, Transcriptional regulation

Development of a PCR assay for the effective detection of Enterocytozoon hepatopenaei (EHP) and investigation of EHP prevalence in Shandong Province, China

Enterocytozoon hepatopenaei (EHP), a recently reported pathogen in the penaeid shrimp, is spreading widely and seriously threatening Penaeus (Litopenaeus) vannamei aquaculture. This study aimed to develop a new and more sensitive polymerase chain reaction (PCR) method for the effective detection of EHP. An EHP PCR assay with a pair of primers specifically amplifying a 358 bp EHP DNA fragment was developed, which was demonstrated to be capable of detecting as low as 2 × 101 copies of EHP and is specific for EHP without cross reaction with DNA samples prepared from five common shrimp pathogens, including white spot syndrome virus (WSSV), infectious hypodermal and haematopoietic virus (IHHNV), hepatopancreatic parvovirus (HPV), infectious myonecrosis virus (IMNV), and yellow head virus (YHV). This new assay is more specific and more sensitive than the previously published EHP PCR methods. With the PCR assay developed in this study, we investigated the prevalence of EHP in four areas of Shandong, China by testing a total of 639 shrimp samples collected from Yantai, Binzhou, Dongying, and Weifang. The results showed that the EHP positive rate reached 51.2%, indicating that EHP is prevalent in shrimp culture in China.